MINERAI, OGY. 
177 
and fome'what dtiftile, both when crade^ 
and when melted. It cannot be decom- 
pofed without fome admixture of fuch fub- 
ftances as attrad the acid of the fea-falt. 
It is found in very thin worked or wrought 
leaves or crufts, at Johan Georgenftadt, in, 
Saxony. 
SECT. CLXXVIIL 
O B s E kvATi o N s on the Si lve bl O it e s. 
Silver may, perhaps, be found mirieralifed in 
the like manner with other rnetals than thefe' here 
enumerated, fuch as with cobalt and bifmuth ^ but 
having no certain knowledge of fuch mineralifa- 
tions, I omit them here. It would be worthy ex- 
amining, if in thofe mine countries where gold 
and filver are found in quantity, other ores do not 
contain a little of thofe metals, more efpecially 
when the particles of filver and gold have not 
been able to extricate themfelves from the other 
minerals, and lie feparate from them in the filTures, 
veins, and fllakes or wranks, that is hollov/ places, 
in the mines. 
Thofe filver ores which are named from earth 
or ftones, wherein the filver is found 5 as, for in- 
ftance, in the Gopfe-dung filver ore, and the Le^ 
herertz ; ought no more to be confidered in a na- 
tural fyftem than other diftindions which are ufed 
at mineral works, and are only names given to 
the ores, according to the feveral changes they 
undergo to make them Ht . for the melting procefs. 
In this our time a mineralifation of filver with 
alcali has been mentioned : it is faid to have been 
found at Annaberg inAuftria: But this difcovery, 
Which is made by a mine-mafter, Mr. Von Jufti, 
N requires 
